The First Alert CO615B is a UL 2034 listed wire-in carbon monoxide alarm designed for use in both residential and institutional settings like hotels, motels, dormitories, and the sleeping rooms of hospitals. It features an advanced electrochemical carbon monoxide sensor and an 85-decibel horn. The backlit digital display gives visual confirmation of CO levels. This unit is designed to be plugged directly into a standard non-switch outlet, and the red LED indicator confirms power is on or the unit is in alarm mode. This unit includes 2 AA batteries as a battery backup to keep you protected even during power outages and functions in temperatures from 40 degrees to 100 degrees Fahrenheit and in humidity up to 95%. The 5-year warranty guarantees years of confidence in the safe air quality in the home or institution.